Fluids?
What's under the dirt? Bare wood? Stained wood? Painted? Normally, I think of bleach for mildew, but you don't want to bleach the wood unevenly unless you plan to go back and stain it again. What's nearby? Will overspray harm nearby plants and or lawn? Pets?
I think most commercial deck cleaners are heavy into bleach as well as being heavy into price.
Simple Green is usually safe, but a bleach cleaning may serve as a preventative for mildew return. You may have to test in small areas first.
I wouldn't be surprised if the pressure washer without additives could do the job and then the sealer on top for future protection.
After many years cleaning and sealing a long shaded ramp, I finally covered it with opaque (solid color) stain. It requires re-cover in heavy wear areas, but generally looks better than the old un-coated wood.
|